Vacuum cleaner



May 8, 1956 F. s. HOWARD 2,744,679

VACUUM CLEANER Filed Nov. 17, 1951 I 5 s s 1 jzwefi'f- 941ml 8 /M ,Bjmyllm y 8, 1956 F. s. HOWARD 2,744,679

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May 8, 1956 F. s. HOWARD 2,744,679

VACUUM CLEANER Filed Nov. 17, 1951 s Sheets-Sheet s United States Patent 2,744,679 I VACUUM CLEANER Frank S. Howard, Chicago, 11]., assignor to BirtmanElectric Company, a corporation of Illinoisv Application November 17, 1951, Serial No. 256,874

2 Claims. Cl. 230-127 This invention relates to a centrifugal fan and particularly to a fan for a vacuum cleaner including a rotatable way from the impeller. Thus, the impeller is separated from the remainder of the cleaner casing forming the exhaust passage. I have found that in the ordinary cleaners string, hair, threads and the like often enter behind the impeller and become wedged therein orwrapped around the shaft on which the impeller is mounted for rotation.

In order to overcome the above described difficulties, I have invented a structurewherein a shield is attached to the casing portion forming a part of the air exhaust passageway from the impeller and extending over the substantiallycircular peripheral rim of the impeller to prevent foreign material entering between the impeller and this exhaust passage forming means. The shield is spaced from the peripheral rim a distance'suificient to permit the normal play in the motor shaft and thus in the impeller.

In a preferred construction the peripheral rim is curved inwardly from the axial portions of the impeller and the shield is located at the inner edge .of this curved part.

The invention will be described as shown in the accompanying drawings. I Of the drawings: Fig. 1 is a'fragmentary longitudinal vertical section through a vacuum cleaner embodying the invention; Fig 2 is 'a front elevation of the rotatable impeller and associated structure; Fig. 3 is a fragmentary enlarged section taken substantially along line 3--3 .of Fig. 2; Fig. 4 is a fragmentary enlarged elevational view showing the rotatable cutterblade approaching thefixed cutter blade; Fig- 5 is a section taken substantially along line 51-5 of Fig. 1; and Fig. 61 is a rear elevational view of the motor. casing and associated structure of thecleaner. I

In the embodiment shown in the accompanying drawings the vacuum cleaner 10 is supported onspaccd Wheels 11 and is adapted to be propelled by meansof a handle 12. The cleanerincludes a casing 13 within anouter housing 14. The casing 13 is provided with a removable front portion 13a having roughly the shape of a truncated cone with the base portion arranged substantially vertically. The front portion 13a'has an enlarged circular opening 1312 at the front or apex thereof.

Spaced inwardly from the front portion 13a and sub- 2,744,679 Patented May 8, 1956 and the second casing portion 15. The outer edge of each blade 17 is'substantially horizontal, as shown in Fig. l, and the base of the conical fan 16 is curved rearwardly so that these horizontal edges are substantially tangential .to this curved portion.

The casing 13 rearwardly of the removable casing portion 13:: is provided with an exhaust passage 18 of generally helical shape. As is shown in Fig. 5, "this exhaust passage which is of expanding cross section communicates through almost 360- with the exhaust from the centrifugal impeller or fan 16. The entrance to the helical exhaust passage 18 is at the bottom of the cleaner in the area indicated at 19 in Fig. 5. Air propelled by the rotating fan 16 flows from the nozzle 20 of the cleaner upwardly through the enlarged circular opening 13b outwardly between the casing portions 13!: and 15 and into the exhaust passage '18 through substantially the entire 360 of the periphery of the fan 16. The exhaust passage is of expanding cross sectional area from the entrance 19 to the exit 21 which is adapted to be placed in communication with a dust bag in the usual manner.

It has been found in actual tests that the entrance 19 to the exhaust passage operates as a barrier against which pieces of paper and other foreign material tend to gather.

If not removed, this paper and the like accumulates. to

such a large amount that it interferes with the eflicient operation of the cleaner. In order to remove this foreign material there is provided a fixed cutter blade 22 attached as by screws 23 to the entrance 19 of the exhaust passage so that the cutting edge 22a extends beyond the casing at this entrance in position to have paper and otherioreign material deposited thereon. This fixed blade has the cutting edge 22a concave with the point of deepest curvature being adjacent to the impeller 16.

Cooperating with the fixed cutter blade 22 is a sec-,

ond cutter blade 24 fastened .to the impeller 16 for rotation therewith. The second cutter blade is provided with an inclined cutting edge adapted to cooperate with the cutting edge 22a of the fixed cutter blade 22 and sever paper and the like deposited thereon. As can be seen from Fig. 4, the concave cutter edge 22:: and the sloped cutting edge 24a cooperate to have'a slicing action or a scissors effect. In providing the exhaust passage 18 with a cross sectional area increasing in size from the entrance 19 of the exhaust passage to the exit 21 thereof, the rear wall 130 forming the exhaust passage is helically curved. Added cross sectional area is also provided by positioning the inner casing wall 13d inwardly with respect to the outer edge 17a of the blades 17. This gives the effect of im mediately enlarging the exhaust passage from the impeller 16 and speeds the volume flow of air.

In order to rotate the fan or impeller 16, this impeller is mounted on a shaft 25 which serves as an extension of the motor shaft 26. This shaft 25 extends through the opening 13b and is providedwith a spindle 27 for driving a belt 28. This belt passes around the spindle 27 and then around the hub of a brush 29 for rotating this brush.

In theordinary cleaner of the general type shown in the drawings it has been found that hair, string and the like Work their way in behind the impeller 16 and bestantially parallel thereto over a portion of its surface manner, as shown in Fig. 2, and extend slightly less than the full distance between the front casing portion 13a come wrapped around the rotating shaft 25 or around the inner surface of the hub of the impeller 16 through which the shaft 25 extends. Inorder to prevent this action there is provided a shield 30 attached to the casing that forms a part of the exhaust passage with this shield extending over the peripheral rim of the impeller 16 to prevent foreign material entering behind the impeller. This shield is adjacent to the periphery of the impeller and overlaps the peripheral area of the impeller, as shown most clearly in Fig. 3. The shield is spaced from the peripheral rim a distance sufficient to permit normal play in the shaft 25 and thus the impeller 16. In the embodiment shown in the drawings the shield includes an annular planar portion 30a extending outwardly from the inner wall 13d of the exhaust passage 18 and a cylindrical portion 30b overlapping the peripheral area or rim of the impeller 16. In the embodiment shown the casing portion 15 that is behind the impeller 16 is attached to the remainder of the casing in which the exhaust passage 18 is located by means of spaced bolts 31. The planar portion 30a of the shield is clamped between the casing portion 15 and the casing portion in which the exhaust passage 18 is formed.

In order to provide efiicient ventilation of the motor 32', there is provided a centrifugal ventilating fan 33 mounted on the motor shaft 26 immediately behind the front shaft bearing 34. Air is directed into the center of this fan 33 by means of a battle 35 located inwardly of the fan 33 and the wall 13d defining the exhaust air passage 18 from the nozzle 20 of the cleaner. This balfie 35 has a substantially cylindrical portion 35a positioned inwardly of the wall 13d and a substantially annular planar portion 35b located at the inner end of the portion 35a. This planar portion 351; extends to the wall 13d to make an effective sealing contact therewith. On the front edge of the cylindrical portion 35a there is pro vided another planar portion 350 extending inwardly and located just rearwardly of the rear edges of the blades 33a of the fan 33. This planar portion 350 is provided with an air inlet opening 35d concentric with the fan 33. This circular opening 35d is located just outwardly of the innermost edges 33b of the fan blades 33a. With this construction, rotation of the fan 33 causes air to be drawn across the motor 32 and through the opening 35d in the-other planar portion 35c and then forced outwardly by the rotating blades 33a into the passage 36 defined by the inner surface of the wall 13d, the cylindrical portion 35a and the first planar portion 35b.

In order to provide entrance and exhaust of the motor cooling air, the frame 37 containing the motor 32 is provided on its rear surface with air entrance openings 37a, 37b, 37c, 37d, and 372. When the fan 33 is in operation, air is drawn through these openings 37a to 37e, inclusive, where it flows across the motor 32 and through the shield opening 35d into the center of the centrifugal fan 33. From this fan, the air flows outwardly between guide means formed by the second casing portion 15 and baffle planar portion 350 and then through the passage 36. The air then passes out an opening 38 (Fig. to the atmosphere. This opening is formed by cutting away a portion of the casing 13d just to the rear and upwardly of the exhaust passage entrance 19. This cut-out part forming the opening 38 extends arcuately around the fan 33 about 90 (Fig. 5) and is located to the right of the casing forming the exhaust air passage when the cleaner is viewed from the front of Fig. 1.

The baflle 35 and associated structure have a multiple function. In one respect, by locating the cylindrical portion 35a adjacent the motor 32 the shield serves to direct air across the motor for maximum cooling. Similarly, the inwardly directed planar portion 35c also aids in directing air across the motor. The combination of the portion 35a and the planar portions 35b and 35c also provide one side of the outlet passage 36 for exhausting the air from the centrifugal fan 33. By locating the guide means including the planar portion 35c adjacent to the blades 33a the fan 33 operates at maximum efficiency to draw a strong air current across the motor in substantially streamline flow. By locating the inlet opening 35d in the battle adjacent the inner edges of the blades 33a, all of the air is directed to the inner edges of the blades 33a so that maximum suction and thus maximum air flow is obtained.

The thread shield 30 that extends over the peripheral rim of the impeller 16 is spaced from this rim a distance sutficient to permit the usual and normal play in the motor shaft 26 and thus in the impeller. Despite this provision for play I have found that substantially no threads or other fibrous material enter between the shield and the impeller. This space apparently defines an area of back air pressure. Furthermore, the inward curvature of the peripheral area of the fan 16 and the barrier effect of the front edge of the shield 30 apparent- 1y cause air currents to carry foreign material away from this space.

The ventilating means for the motor including the fan 33, bafiie 35 and. associated structure is described and claimed in Addison Ballard Bradley, Jr., application Serial No. 256,726, filed November 16, 1951. The cutter mechanism including the blades 22 and 24 and associated structure is described and claimed in Charles H. Sparklin application Serial No. 256,701, filed November 16, 1951.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description unless otherwise specified but; rather be construed broadly within its spirit and scope as set out in the accompanying claims.

I claim:

1. In a vacuum cleaner, a centrifugal fan including an impeller rotatable about a central axis and having a substantially circular edge and an outer surface carrying fan blades, the outer surface being of generally convex configuration having a rearwardly extending sharply curved peripheral annular area adjacent to said edge extending over a major portion of said impeller outer surface, a first casing wall portion adjacent to and rearwardly of said edge and forming a part of one side of a fluid exhaust passageway, the fluid exhaust passageway extending over said impeller outer surface and first casing wall portion and rearwardly thereof, a second casing wall portion spaced from said impeller outer surface and first casing wall portion defining the other side of said passageway opposite to said impeller, the second casing wall portion being curved similarly to said impeller and being spaced substantially uniformly therefrom in the region opposite to said peripheral annular area and said edge, and a thread shield extending forwardly from the first casing wall portion substantially parallel to the flow of air in the general area of said shield, the shield extending in an upstream direction and overlapping said edge of said impeller but spaced therefrom a distance sufiicient to permit normal play in the impeller, the fluid in said passageway flowing over the outer surface of the impeller and the overlapping extended edge of the shield and thereby establishing a zone of back fluid pressure between the shield and impeller due at least in part to the curvature of said peripheral annular area and corresponding part of said passageway to provide resistance to the entrance of foreign material between the shield and the impeller.

2. The vacuum cleaner of claim 1 wherein said first casing wall portion that is adjacent to and rearwardly of said shield is spaced laterally inwardly of said edge and said shield to aid further in establishing said zone of back fluid pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,342,592 Orr June 8, 1920 1,918,400. Kitto July 18, 1933 2,017,905. -Kitto Oct. 22, 1935 2,040,188 Smellie May 12, 1936 2,099,172 McCabe et al Nov. 16, 1937 2,224,205 Whitaker Dec. 10, 1940 2,309,583 Frantz Ian. 26, 1943 

